Segment Information (Schedule Of Segment Reporting Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 851,307	$ 1,425,369	$ 1,478,857
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	580,129	925,082	970,488
Depreciation, depletion, amortization and accretion	146,793	196,459	278,439
General and administrative expenses	222,465	268,226	276,468
Reduction in value of assets	26,897	17,185	322,713
Income (loss) from operations	(172,032)	18,417	(369,251)
Interest income (expense), net	(92,399)	(98,312)	(99,477)
Reorganization expenses	(21,616)
Other income (expense)	(9,229)	(2,484)	(1,678)
Loss from operations before income taxes	(295,276)	(82,379)	(470,406)
Drilling Products And Services [Member]
Segment Reporting Information [Line Items]
Total revenues	281,397	411,573	383,719
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	97,894	154,503	148,019
Depreciation, depletion, amortization and accretion	61,526	83,999	112,111
General and administrative expenses	51,332	60,094	53,688
Reduction in value of assets	599
Income (loss) from operations	70,046	112,977	69,901
Loss from operations before income taxes	70,046	112,977	69,901
Onshore Completion And Workover Services [Member]
Segment Reporting Information [Line Items]
Total revenues	130,798	341,297	406,248
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	123,443	274,162	315,291
Depreciation, depletion, amortization and accretion	22,301	33,699	68,183
General and administrative expenses	16,326	25,621	24,386
Reduction in value of assets	1,857	8,122	227,801
Income (loss) from operations	(33,129)	(307)	(229,413)
Reorganization expenses	(1,606)
Loss from operations before income taxes	(34,735)	(307)	(229,413)
Production Services [Member]
Segment Reporting Information [Line Items]
Total revenues	276,329	405,830	418,525
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	230,939	328,527	342,420
Depreciation, depletion, amortization and accretion	39,867	51,370	66,993
General and administrative expenses	30,292	29,622	41,499
Reduction in value of assets	7,558	2,055	92,252
Income (loss) from operations	(32,327)	(5,744)	(124,639)
Reorganization expenses	(490)
Loss from operations before income taxes	(32,817)	(5,744)	(124,639)
Technical Solutions [Member]
Segment Reporting Information [Line Items]
Total revenues	162,783	266,669	270,365
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	127,853	167,890	164,758
Depreciation, depletion, amortization and accretion	19,329	22,665	25,653
General and administrative expenses	44,660	59,587	57,600
Reduction in value of assets	14,900	7,008
Income (loss) from operations	(43,959)	9,519	22,354
Interest income (expense), net	4,539	4,172	3,915
Loss from operations before income taxes	(39,420)	13,691	26,269
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, amortization and accretion	3,770	4,726	5,499
General and administrative expenses	79,855	93,302	99,295
Reduction in value of assets	1,983		2,660
Income (loss) from operations	(132,663)	(98,028)	(107,454)
Interest income (expense), net	(96,938)	(102,484)	(103,392)
Reorganization expenses	(19,520)
Other income (expense)	(9,229)	(2,484)	(1,678)
Loss from operations before income taxes	$ (258,350)	$ (202,996)	$ (212,524)